#include <iostream>

using namespace std;

/*
    函数常见形式
    1、无参无反
    2、有参无反
    3、无参有反
    4、有参有反
*/
void test01()
{
    cout << "this is test01" << endl;
}

void test02(int a)
{
    cout << "this is test02 a = " << a << endl;
}

int test03()
{
    cout << "this is test03" << endl;
    return 1000;
}

int test04(int b)
{
    cout << "this is test04 b = " << b << endl;
    return 2000;
}

int main(void)
{
    test01();
    test02(100);
    int num1 = test03();
    cout << "num1 = " << num1 << endl;
    int num2 = test04(200);
    cout << "num2 = " << num2 << endl;

    return 0;
}